The subject matter disclosed herein relates to solutions for improving current spreading in organic substrates. More specifically, the subject matter disclosed herein relates to distributing current at a metal-solder interface.
Once formation of semiconductor devices and interconnect structures on a semiconductor wafer (substrate) is complete, the semiconductor wafer is diced into semiconductor chips, or “dies.” Semiconductor chips are then packaged to facilitate mounting on a circuit board. A “package” is a supporting element for the semiconductor chip that provides mechanical protection and electrical connection to a separate assembly system such as the circuit board. One form of packaging technology currently used is Controlled Collapse Chip Connection (C4) packaging, which employs C4 balls each of which contacts a C4 pad on the semiconductor chip and another C4 pad on a packaging substrate. These packaging substrates may help to provide an electrical link between the semiconductor chip and a system board of a computer.
However, C4 packaging poses reliability concerns because both C4 balls and C4 pads are susceptible to electromigration. Electromigration is the movement of a material due to gradual drifting of metal ions in a metallic conductor. As current flows through the metallic conductor, the electrons conducting that current transfer their momentum to the conductive material and may over time create a gap between the C4 pad and the C4 ball. This gap may adversely affect the performance of the semiconductor device.